Single-die flip-chip devices are readily cooled using heat sinks, often in combination with integrated heat spreaders (IHS), fans, heat pipes, and, in extreme cases, liquid heat exchangers. Stacked-die devices, including 3D through-silicon-via (TSV) assemblies, are more difficult to cool. While the top die in the 3D stack may be placed in intimate thermal contact with a heat spreader, heat sink, or heat pipe, the interposed die (the die sandwiched between substrate and the top die) does not have a low resistance thermal path along which to dissipate heat. Poor heat rejection from the interposed die places severe design constraints on next-generation 3D TSV stacked-die architectures, as it basically dictates that high-power die (e.g., CPU) must be placed on top of the stack. To optimize performance of 3D TSV CPU products, flexibility to design the CPU die as the interposed die is strongly desired and for this, a thermal solution for adequately cooling a high-power interposed die in a 3D TSV stacking arrangement is needed.
For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the discussion of the described embodiments of the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. The same reference numerals in different figures denote the same elements.
The terms “first,” “second,” “third,” “fourth,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Similarly, if a method is described herein as comprising a series of steps, the order of such steps as presented herein is not necessarily the only order in which such steps may be performed, and certain of the stated steps may possibly be omitted and/or certain other steps not described herein may possibly be added to the method. Furthermore, the terms “comprise,” “include,” “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein. The term “coupled,” as used herein, is defined as directly or indirectly connected in an electrical or non-electrical manner. Objects described herein as being “adjacent to” each other may be in physical contact with each other, in close proximity to each other, or in the same general region or area as each other, as appropriate for the context in which the phrase is used. Occurrences of the phrase “in one embodiment” herein do not necessarily all refer to the same embodiment.